Relativistic effects in K-shell electron impact ionization

Previously developed BEB, RBEB, DM and recently developed RDM models are employed for the computation of cross-sections of electron impact single K-shell ionization of atoms with atomic numbers from Z = 19 to 103 to augment the work recently done involving atoms with Z = 6 to 40. The calculated cross-sections are compared with the available experimental data over a wide energy range up to 1000 MeV. The RDM model with simple relativistic factor is found to be at least as good as the DM model with a more complex factor up to about 60 MeV. However, the latter one is found to work satisfactorily up to about 1000 MeV.